Correlation between Clinical Outcomes and Baseline CT and CT Angiographic Findings in the SWIFT PRIME Trial

EMS Bypass to Endovascular Stroke Centers is Associated with Shorter Time to Thrombolysis and Thrombectomy for LVO Stroke

OBJECTIVES

Large vessel occlusion (LVO) strokes may be eligible for treatment with intravenous thrombolysis (IVT) and endovascular therapy (EVT). Patients selected for treatment have better neurologic outcomes with EVT, and delays in this therapy lead to worse outcomes. However, EVT is offered at a limited number of hospitals, referred to as endovascular stroke centers (ESC). This poses a difficult decision for EMS: to take potential stroke patients to the closest primary stroke center (PSC) or longer transport time to a more distant ESC. We hypothesized that patients with LVO stroke undergoing EVT transported directly to an ESC would have more favorable outcomes as measured by the modified Rankin scale (mRS) at 90 days, compared to transport to a PSC followed by transfer to an ESC.

METHODS

The OPUS-REACH consortium examined transportation patterns and outcomes in patients with LVO stroke who received endovascular treatment. This cohort includes 2400 patients with LVO stroke throughout eight endovascular centers in the Northeast U.S. from 2015 to 2020. All patients enrolled in the OPUS-REACH database were eligible for inclusion. Patients were excluded if they were missing the pickup address, had an in-hospital stroke, or arrived via mobile stroke unit. The remaining patients were separated into two groups: the bypass group, with transportation by EMS to an ESC by bypassing PSC, and the non-bypass group, with initial transport to PSC and interfacility transport to an ESC. The primary outcome was the modified Rankin scale (mRS) at 90 days, where 0-2 was defined as "good".

RESULTS

The primary outcome did not reach significance with 40% of the bypass group as compared with the 33.1% of the non-bypass group having a "good" outcome. However, the bypass group underwent shorter times from last-known-well to both thrombolysis (120.9 vs 153.3 min, p < 0.001) and thrombectomy (356.1 vs 454.8 min, p = 0.001).

CONCLUSIONS

In patients with LVO stroke who undergo thrombectomy, EMS transport directly to an ESC results in shorter time thrombectomy, although we did not observe a difference in 90-day functional outcomes. Additionally, bypass to reach a more capable endovascular stroke center does not delay administration of IVT from time of LKW.

Circle of Willis variation and outcome after intra-arterial treatment

Background

Intra-arterial treatment (IAT) improves outcomes in acute ischaemic stroke. Presence of collaterals increases likelihood of good outcome. We investigated whether variations in the circle of Willis (CoW) and contributing carotid arteries influence outcome in patients who had a stroke treated with IAT.

Methods

CT angiography data on patients who had an acute stroke treated with IAT were retrospectively collected. CoW was regarded complete if the contralateral A1 segment, anterior communicating artery and ipsilateral posterior communicating artery were fully developed, and the P1 segment was visible. Carotid artery contribution was studied with a self-developed carotid artery score ranging from 0 to 2 depending on the number of arteries supplying the occluded side of the CoW. Good clinical outcome was defined as modified Rankin Score ≤2 and measured at discharge and 3 months. We calculated risk ratios for the relation between completeness of the CoW, carotid score and good outcome, and performed a trend analysis for good outcome according to the carotid score.

Results

126 patients were included for analysis. Patients with a complete and incomplete CoW had a comparable risk for good outcome at discharge and 3 months. A higher carotid score was associated with a higher likelihood of good clinical outcome (p for trend 0.24 at discharge and 0.05 at 3 months).

Conclusion

In patients with acute ischaemic stroke treated with IAT, chances of good clinical outcome tended to improve with number of carotid arteries supplying the cerebral circulation. Completeness of the CoW was not related to clinical outcome.

Optimizing Prehospital Stroke Systems of Care-Reacting to Changing Paradigms (OPUS-REACH): a pragmatic registry of large vessel occlusion stroke patients to create evidence-based stroke systems of care and eliminate disparities in access to stroke care

Background

Large vessel occlusion (LVO) strokes are best treated with rapid endovascular therapy (EVT). There are two routes that LVO stroke patients can take to EVT therapy when transported by EMS: primary transport (ambulance transports directly to an endovascular stroke center (ESC) or secondary transport (EMS transports to a non-ESC then transfers for EVT). There is no clear evidence which path to care results in better functional outcomes for LVO stroke patients. To find this answer, an analysis of a large, real-world population of LVO stroke patients must be performed.

Methods

A pragmatic registry of LVO stroke patients from nine health systems across the United States. The nine health systems span urban and rural populations as well as the spectrum of socioeconomic statuses. We will use univariate and multivariate analysis to explore the relationships between type of EMS transport, socioeconomic factors, and LVO stroke outcomes. We will use geographic information systems and spatial analysis to examine the complex movements of patients in time and space. To detect an 8% difference between groups, with a 3:1 patient ratio of primary to secondary transports, 95% confidence and 80% power, we will need approximately 1600 patients.

The primary outcome is the patients with modified Rankin Scale (mRS) ≤ 2 at 90 days. Subgroup analyses include patients who receive intravenous thrombolysis and duration of stroke systems. Secondary analyses include socioeconomic factors associated with poor outcomes after LVO stroke.

Discussion

Using the data obtained from the OPUS-REACH registry, we will develop evidence based algorithms for prehospital transport of LVO stroke patients. Unlike prior research, the OPUS-REACH registry contains patient-level data spanning from EMS dispatch to ninety day functional outcomes. We expect that we will find modifiable factors and socioeconomic disparities associated with poor outcomes in LVO stroke. OPUS-REACH with its breadth of locations, detailed patient records, and multidisciplinary researchers will design the optimal prehospital stroke system of care for LVO stroke patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-022-02653-x.

Imaging in Acute Anterior Circulation Ischemic Stroke: Current and Future

Clinical trials on acute ischemic stroke have demonstrated the clinical effectiveness of revascularization treatments within an appropriate time window after stroke onset: intravenous thrombolysis (NINDS and ECASS-III) through the administration of tissue plasminogen activator within a 4.5-hour time window, endovascular thrombectomy (ESCAPE, REVASCAT, SWIFT-PRIME, MR CLEAN, EXTEND-IA) within a 6-hour time window, and extending the treatment time window up to 24 hours for endovascular thrombectomy (DAWN and DEFUSE 3). However, a substantial number of patients in these trials were ineligible for revascularization treatment, and treatments of some patients were considerably futile or sometimes dangerous in the clinical trials. Guidelines for the early management of patients with acute ischemic stroke have evolved to accept revascularization treatment as standard and include eligibility criteria for the treatment. Imaging has been crucial in selecting eligible patients for revascularization treatment in guidelines and clinical trials. Stroke specialists should know imaging criteria for revascularization treatment. Stroke imaging studies have demonstrated imaging roles in acute ischemic stroke management as follows: 1) exclusion of hemorrhage and stroke mimic disease, 2) assessment of salvageable brain, 3) localization of the site of vascular occlusion and thrombus, 4) estimation of collateral circulation, and 5) prediction of acute ischemic stroke expecting hemorrhagic transformation. Here, we review imaging methods and criteria to select eligible patients for revascularization treatment in acute anterior circulation stroke, focus on 2019 guidelines from the American Heart Association/American Stroke Association, and discuss the future direction of imaging-based patient selection to improve treatment effects.

Quantitative collateral assessment evaluated by cerebral blood volume measured by CT perfusion in patients with acute ischemic stroke

OBJECTIVES

Collateral status (CS) is considered a predictor of clinical outcome after reperfusion therapy (RT) in patients with acute ischemic stroke (AIS). We proposed a quantitative assessment of CS using cerebral blood volume (CBV) measured by computed tomography perfusion (CTP) imaging.

MATERIALS AND METHODS

This retrospective study was approved by the Institutional Review Board. Between February 2019 and September 2020, 60 patients with anterior circulation large-vessel occlusion who presented to our institution within 8 h after stroke onset were included. The ratio of the average CBV values in the affected middle cerebral artery (MCA) territories to the unaffected side was defined as the CBV ratio. CS was assessed by scores from previously reported qualitative scoring systems (Tan & regional leptomeningeal collateral (rLMC) scores).

RESULTS

The CBV ratio was an independent factor contributing to a good functional outcome (P<0.01) and was significantly correlated with the Tan score (ρ=0.73, P<0.01) and the rLMC score (ρ=0.77, P<0.01). Among the patients with recanalization, the CBV ratio was a useful parameter that predicted both a good functional outcome (area under the receiver operating characteristic curve (AUC-ROC), 0.76; 95% CI, 0.55-0.89) and a good radiological outcome (AUC-ROC, 0.90; 95% CI, 0.72-0.97), and it was an independent predictor for good radiological outcome (OR: 4.38; 95% CI:1.29-14.82; P<0.01) in multivariate models.

CONCLUSIONS

The CBV ratio is a suitable parameter for evaluating CS quantitatively for patients with AIS that can predict patient response to recanalization.

The impact of native leptomeningeal collateralization on rapid blood flow recruitment following ischemic stroke

The leptomeningeal collateral status is an independent predictor of stroke outcome. By means of optical coherent tomography angiography to compare two mouse strains with different extent of native leptomeningeal collateralization, we determined the spatiotemporal dynamics of collateral flow and downstream hemodynamics following ischemic stroke. A robust recruitment of leptomeningeal collateral flow was detected immediately after middle cerebral artery (MCA) occlusion in C57BL/6 mice, with continued expansion over the course of seven days. In contrast, little collateral recruitment was seen in Balb/C mice during- and one day after MCAO, which coincided with a greater infarct size and worse functional outcome compared to C57BL/6, despite a slight improvement of cortical perfusion seven days after MCAO. Both strains of mice experienced a reduction of blood flow in the penetrating arterioles (PA) by more than 90% 30-min after dMCAO, although the decrease of PA flow was greater and the recovery was less in the Balb/C mice. Further, Balb/C mice also displayed a prolonged greater heterogeneity of capillary transit time after dMCAO in the MCA territory compared to C57BL/6 mice. Our data suggest that the extent of native leptomeningeal collaterals affects downstream hemodynamics with a long lasting impact in the microvascular bed after cortical stroke.

Identification of Predictors for Hemorrhagic Transformation in Patients with Acute Ischemic Stroke After Endovascular Therapy Using the Decision Tree Model

Purpose

This study aimed to identify independent predictors for the risk of hemorrhagic transformation (HT) in arterial ischemic stroke (AIS) patients.

Methods

Consecutive patients with AIS due to large artery occlusion in the anterior circulation treated with mechanical thrombectomy (MT) were enrolled in a tertiary stroke center. Demographic and medical history data, admission lab results, and Circle of Willis (CoW) variations were collected from all patients.

Results

Altogether, 90 patients were included in this study; among them, 34 (37.8%) had HT after MT. The final pruned decision tree (DT) model consisted of collateral score and platelet to lymphocyte ratios (PLR) as predictors. Confusion matrix analysis showed that 82.2% (74/90) were correctly classified by the model (sensitivity, 79.4%; specificity, 83.9%). The area under the ROC curve (AUC) was 81.7%. The DT model demonstrated that participants with collateral scores of 2–4 had a 75.0% probability of HT. For participants with collateral scores of 0–1, if PLR at admission was <302, participants had a 13.0% probability of HT; otherwise, participants had an 75.0% probability of HT. The final adjusted multivariate logistic regression analysis indicated that collateral score 0–1 (OR, 10.186; 95% CI, 3.029–34.248; p < 0.001), PLR (OR, 1.005; 95% CI, 1.001–1.010; p = 0.040), and NIHSS at admission (OR, 1.106; 95% CI, 1.014–1.205; p = 0.022) could be used to predict HT. The AUC for the model was 0.855, with 83.3% (75/90) were correctly classified (sensitivity, 79.4%; specificity, 87.3%). Less patients with HT achieved independent outcomes (mRS, 0–2) in 90 days (20.6% vs. 64.3%, p < 0.001). Rate of poor outcomes (mRS, 4–6) was significantly higher in patients with HT (73.5% vs. 19.6%; p < 0.001).

Conclusion

Both the DT model and multivariate logistic regression model confirmed that the lower collateral status and the higher PLR were significantly associated with an increased risk for HT in AIS patients after MT. PLR may be one of the cost-effective and practical predictors for HT. Further prospective multicenter studies are needed to validate our findings.

Optimizing Outcome Prediction Scores in Patients Undergoing Endovascular Thrombectomy for Large Vessel Occlusions Using Collateral Grade on Computed Tomography Angiography

BACKGROUND

Although several outcome prediction scores incorporated with pretreatment variables have been developed for acute ischemic stroke (AIS) patients, there is not currently a prediction score that includes pretreatment imaging that can show salvageable brain tissue.

OBJECTIVE

To evaluate whether addition of the collateral grade on computed tomography angiography to previously published prediction scores could increase accuracy of clinical outcome prediction in endovascular thrombectomy (EVT) for AIS.

METHODS

This study used a retrospective multicenter registry for patients undergoing EVT for anterior circulation large vessel occlusion. Three previously published outcome prediction scores (Houston intra-arterial therapy 2, HIAT2; totaled health risks in vascular events, THRIVE; and Pittsburgh response to endovascular therapy, PRE scores) were tested in this study. Using 482 deprivation cohorts, areas under the receiver operating characteristic curves (AUC-ROCs) were compared between prediction scores with/without collateral grades in predicting the poor outcomes (modified Rankin Scale 4-6 at 3-mo follow-up) after EVT. We developed modified prediction scores by adding the collateral grade, and their advancement of outcome prediction was validated using 208 independent validation cohorts.

RESULTS

AUC-ROCs of HIAT2, THRIVE, and PRE scores that incorporated with collateral grade were superior in predicting poor outcomes when compared to that of the unmodified scores (P < 0.001). In modified prediction models, 3, 3, and 10 points were added for poor collateral grade to HIAT2, THRIVE, and PRE score. Modified models outperformed unmodified models in testing of the validation cohorts (P < 0.001).

CONCLUSION

The addition of the collateral grade to outcome prediction scores resulted in better prediction of poor outcome after EVT for AIS compared to the prediction scores alone.

Prediction contribution of the cranial collateral circulation to the clinical and radiological outcome of ischemic stroke

BACKGROUND AND AIM

The extent of penumbra tissue and outcome in stroke patients depend on the collateral cranial vasculature. To provide optimal individualized care for stroke patients in the emergency room setting we investigated the predictive capability of a stringent evaluation of the collateral vessels in ischemic stroke on clinical outcome and infarct size.

METHODS

We retrospectively studied uniform clinical and radiological data of 686 consecutive patients admitted to the emergency department with suspected acute ischemic stroke. Cranial collateral vasculature status was graded using the initial CT-angiography. Outcome was measured by mRS, NIHSS and final infarct size at hospital discharge. All data were used to build a linear regression model to predict the patients´ outcome.

RESULTS

Univariate and multivariate analyses showed significant effects of the whole brain collateral vessel score on all outcome variables. Atherosclerosis and piale collateral status were associated with the final infarct volume (FIV). Atherosclerosis and age were associated with the NIHSS at discharge. The presence of atherosclerosis, glucose level on admission and age were associated with the mRS at discharge. The multivariate models were able to predict 29% of the variance of the mRS at discharge, 24% of the variance in FIV and 17% of the variance of the NIHSS at discharge. The whole brain collateral status and the presence of atherosclerosis were the most relevant predictors for the clinical and radiological outcome.

CONCLUSION

The whole brain collateral vasculature status is clearly associated with clinical and radiological outcome but in a multivariate model seems not sufficiently predictive for FIV, mRS and NIHSS outcome at discharge in non-preselected patients admitted to the emergency department with ischemic stroke.

Value of thrombus imaging in predicting the outcomes of patients with large-vessel occlusive strokes after endovascular therapy

BACKGROUND

Acute ischemic stroke leads to serious long-term disability and high mortality, especially in patients with large-vessel occlusive strokes. Nowadays, endovascular therapy is considered as an alternative treatment for these patients. Several studies have used thrombus characteristics based on non-contrast computed tomography (NCCT) and computed tomography angiography (CTA) to predict prognosis in ischemic stroke. We conducted a systematic review to identify potential imaging predictive factors for successful recanalization and improved clinical outcome after endovascular therapy in patients with large-vessel occlusion (LVO) in anterior arterial circulation.

METHODS

The PubMed databases were searched for related studies reported between September 18, 2009, and September 18, 2019.

RESULTS

We selected 11 studies on revascularization and 12 studies on clinical outcome. Patients with thrombus of higher Hounsfield unit (HU), shorter length, higher clot burden score, and increased thrombus permeability may achieve higher recanalization and improved clinical outcome, but the matter is still under debate.

CONCLUSION

Imaging of thrombus can be used as an aseessment tool to predict the outcomes and it needs further studies in the future.

Collateral grade of the Willis' circle predicts outcomes of acute intracranial internal carotid artery occlusion before thrombectomy

BACKGROUND AND PURPOSE

Endovascular mechanical thrombectomy (EVMT) shows significant promise in improving acute ischemic stroke (AIS) with proximal artery occlusion, but outcomes have been variable. We explored the patients treated by thrombectomy to investigate the association between a favorable clinical outcome of EVMT in intracranial internal carotid artery occlusion (iICAO) and a set of predictors.

METHODS

A total of 38 iICAO patients treated by EVMTs were analyzed. Primary collateral grades (PCG) at baseline based on the integrity of Willis' circle were categorized into three degrees. The favorable outcomes, measured by modified Rankin scale (mRS), were defined as ≤2 at 90 days. The reperfusion was one of the most important confounders, defined as modified thrombolysis in cerebral infarction (mTICI) ≥ 2b. The other risk factors included demographic characteristics, vascular risk factors, stroke severity, procedural EVMT, and PCG at baseline was adjusted to reveal the association with favorable outcomes.

RESULTS

Of 38 iICAO patients, 65.8% (25 in 38) achieved reperfusion. However, only 31.6% (12/38) achieved favorable outcomes at 90 days. With a PCG3, 61.5% of them achieved favorable outcomes, while only 37.5% of those with PCG2 and PCG1 achieved favorable outcomes (p = .003). In multivariable logistic regression, PCG was revealed as a predictor for favorable outcomes (OR 5.278, p = .019) after adjusting the reperfusion and other factors.

CONCLUSIONS

The PCG based on the integrity of Willis' circle might be an underlying predictor of the prognosis of AIS in patients with iICAO after EVMT. The function of intact anterior communicating artery (AcoA) and ipsilateral posterior communicating artery (PcoA) in favoring prognosis of the iICAO patients might need to be validation in future study.

Differential Benefit of Collaterals for Stroke Patients Treated with Thrombolysis or Supportive Care : A Propensity Score Matched Analysis

PURPOSE

Leptomeningeal collaterals can slow down infarction growth; however, despite good collaterals in the DAWN and DEFUSE 3 trials, outcomes were devastating if reperfusion was not attempted. The aim of this study was to compare the influence of collaterals on morphological and functional outcome in patients with acute middle cerebral artery (MCA) stroke undergoing intravenous thrombolysis (IVT) vs. supportive care (non-IVT).

METHODS

Out of 1639 consecutive patients examined with multiparametric computed tomography (CT) for suspected ischemic stroke, all patients with confirmed MCA stroke who did not undergo endovascular thrombectomy were selected. Propensity score matching (PSM) was used to match IVT and non-IVT treated patients for potential confounders including age, sex, National Institutes of Health Stroke Scale (NIHSS) score on admission, Alberta Stroke Program Early CT Score (ASPECTS), and occlusion site. Regression analysis after PSM was performed to identify independent associations.

RESULTS

After PSM, 90 IVT patients were matched with 90 non-IVT patients. In multivariable regression analysis, a high regional leptomeningeal collateral (rLMC) score was independently associated with lower final infarction volume (FIV) in the IVT group (b = -0.472, p < 0.001) but not in the non-IVT group (b = -0.116, p = 0.327). The trichotomized rLMC scores predicted functional outcome in IVT treated patients (adjusted odds ratio, aOR = 4.57, 95% confidence interval, CI, 1.03-20.32, p = 0.046) but showed no independent association with outcome in the non-IVT group (aOR = 0.69, 95% CI 0.07-6.80, p = 0.753).

CONCLUSION

Good collaterals favored smaller FIV and good functional outcome in IVT treated patients but not in non-IVT treated patients. Good collateral flow may have limited prognostic value if IVT is not administered to attempt reperfusion.

Clinical and Imaging Markers Associated With Hemorrhagic Transformation in Patients With Acute Ischemic Stroke

Background and Purpose—

Hemorrhagic transformation (HT) after acute ischemic stroke may cause severe neurological deterioration and affects functional outcome. Identifying patients most likely to suffer from this complication could potentially be used for future treatment selection. Reperfusion after endovascular therapy could be associated with different risk factors for HT than intravenous thrombolytics as these treatments largely differ. In this study, we aimed to identify clinical and imaging markers that are associated with HT subtypes in the MR CLEAN (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands) population.

Methods—

In this post hoc analysis, all patients with follow-up imaging were included. HT was classified according to ECASS II (European Cooperative Acute Stroke Study). Variables with an association of P <0.1 were included in the multivariable logistic regression to identify clinical and radiological variables associated with petechial hemorrhagic infarction, parenchymal hematoma (PH), and symptomatic intracranial hemorrhage.

Results—

Of the 478 out of 500 included patients in this subanalysis, 46% had HT (n=222). Of these, 66% had hemorrhagic infarction (n=147) and 34% PH (n=75). Symptomatic intracranial hemorrhage was observed in 7.3% (n=35) of all patients. Baseline National Institutes of Health Stroke Scale (odds ratio [OR], 1.05,95% CI, 1.01–1.09 per point) and absent/poor collaterals (OR, 1.90; 95% CI, 1.05–3.42) were significantly associated with hemorrhagic infarction. Increased systolic blood pressure (OR, 1.17; 95% CI, 1.05–1.31 per 10 mm Hg) and atrial fibrillation (OR, 1.94; 95% CI, 1.08–3.48) were associated with PH. Increased systolic blood pressure (OR, 1.28; 95% CI, 1.12–1.48) and antiplatelet use (OR, 2.6; 95% CI, 1.08–6.3) were associated with symptomatic intracranial hemorrhage.

Conclusions—

Clinical and imaging stroke severity parameters were associated with HT, both in hemorrhagic infarction and PH, whereas baseline patients characteristics like systolic blood pressure, atrial fibrillation, and antiplatelet use were only associated with PH or symptomatic intracranial hemorrhage.

Clinical Trial Registration—

URL: http://www.controlled-trials.com . Unique identifier: ISRCTN10888758.

Greater infarct growth limiting effect of mechanical thrombectomy in stroke patients with poor collaterals

OBJECTIVE

Stroke patients with good collateral circulation achieve the best recovery after mechanical thrombectomy (MT) but strict imaging selection may result in untreated patients that could benefit from MT. We assessed whether the extent of collaterals had modifying effects on the amount of ischemic tissue saved from infarction with MT over best medical treatment (BMT).

METHODS

This was a single center cohort of consecutive patients (n=339) with proximal occlusions in the carotid territory. Patients were categorized according to a four point category scale on CT angiography as having good (scores 2-3) or poor (scores 0-1) collaterals. The primary outcome measure was the interaction between collaterals and MT on infarct growth. The secondary outcome assessed the treatment effect of MT over BMT on functional status in relation to collateral status. Safety outcomes were mortality and symptomatic intracranial hemorrhage.

RESULTS

Collaterals had a modifying effect of MT on infarct growth (P=0.004), with a greater reduction in 96 patients with poor collaterals (38.8 mL) than in 243 patients with good collaterals (1.9 mL). There was also a significant (P<0.001) interaction between the effect of MT and functional outcome in relation to collateral status, with more benefits of MT in patients with poor collaterals. MT was associated with lower mortality than BMT in patients with poor collaterals only.

CONCLUSION

Compared with BMT, the use of MT in the early time window in large vessel stroke results in a more substantial limitation of infarct growth in patients with poor collaterals.

Advanced Neuroimaging of Acute Ischemic Stroke: Penumbra and Collateral Assessment

Acute ischemic stroke (AIS) occurs when there is a sudden loss in cerebral blood flow due to embolic or thromboembolic occlusion of a cerebral or cervical artery. Patients with AIS require emergent neuroimaging to guide treatment, which includes intravenous thrombolysis and endovascular mechanical thrombectomy (EMT). Recent advances in AIS treatment by EMT has been driven in part by advances in computed tomography (CT) and MR imaging neuroimaging evaluation of ischemic penumbra and pial collateral vessels. The authors review advanced noninvasive brain imaging by CT and MR imaging for the evaluation of AIS focusing on penumbral and collateral imaging.